In the expected mean return, standard deviation portfolio selection problem, first step is usually to derive set of efficient portfolios, which in space objective function values represented by frontier. With modern methods and software, it an easy task even for thousands assets provided that problem continuous. However, investors often introduce requirement limit number portfolios (portfolio c...

Learning about statistics is a lot like learning about science: the learning is more meaningful if you can actively explore. This series in Advances in Physiology Education provides an opportunity to do just that: we will investigate basic concepts in statistics using the free software package R. Because this series uses R solely as a vehicle with which to explore basic concepts in statistics, ...

In this Journal, Lewis and colleagues introduced a new Reliable Change Index (RCI(WSD)), which incorporated the within-subject standard deviation (WSD) of a repeated measurement design as the standard error. In this note, two opposite errors in using WSD this way are demonstrated. First, being the standard error of measurement of only a single assessment makes WSD too small when practice effect...

In most clinical and experimental studies, the standard deviation (SD) and the estimated standard error of the mean (SEM) are used to present the characteristics of sample data and to explain statistical analysis results. However, some authors occasionally muddle the distinctive usage between the SD and SEM in medical literature. Because the process of calculating the SD and SEM includes differ...

As a nonstatistician, I have watched the discussion on this topic with interest (1–8). Dr. Curren-Everett and others make a clear statement that variability of results should always be reported using the standard deviation (SD) and not the standard error (SE). Others cited above variously agree and disagree with the guidelines published by Dr. Curren-Everett and others. The reasoning provided i...

1 Stylized facts and puzzles Recent empirical research has highlighted a number of regularities, mainly for US data in the post-World-War-II period (but also con…rmed over longer samples and extended to other countries by crosscountries studies). The main relevant stylized facts are the following: 1. " high " real average return on stocks (US S&P index: around 8% annually over 1947-2000) 2. " l...

After Covid-19, the American stock market experienced a big impact. This paper mainly focuses on consequent influence logistics industry in US and investment portfolio them. also aims to compare average return, standard deviation sharp ratio of two classic models: Markowitz model Index before after covid-19. Through analyzing data 10 stocks America Standard Poor 500 as reference from 2019 2021 ...

Many Forth systems provide means to call C functions, but these interfaces are not designed to be portable between platforms: A call to a C library function that works on one platform may fail on the next platform, because the parameter and return value types of the C function may be different. In this paper, we present an interface that avoids this problem: In particular, the actual calls can ...